1. Field of the Invention
The present invention relates to a temperature responsive clutch for a radiator cooling fan of a motor vehicle engine.
2. Description of the Prior Art
In a conventional motor vehicle, the radiator cooling fan is driven constantly by way of pulleys and belts from the crank shaft of the engine. In order to increase engine efficiency, it has been found desirable to drive the cooling fan only when the temperature of the engine reaches a high level. This may be done by providing a fan clutch which is controlled by a temperature sensing element that allows the fan to rotate freely if engine temperature is low and which engages the fan with engine rotation if the temperature is high.
U.S. Pat. Nos. 3,227,254 and 2,838,244 disclose temperature responsive clutches for driving a radiator cooling fan when the temperature is high. The clutches of these patents are of the viscous fluid drive type.